This invention relates to an assembly for cutting a continuous sheet of material covering containers which are continuously conveyed in spaced apart container carriers at a predetermined speed. More particularly, the present invention relates to an assembly which automatically aligns a cutting head mechanism with each container carrier and maintains the alignment as the sheet of material is being cut.
Various types of automated systems are known for automatically filling containers moving along a predetermined path with a product such as food or the like. Individual containers which contain one or more servings of food and are sold either refrigerated or frozen are becoming increasingly popular. Such containers are typically processed on an assembly line, with the filling of the containers usually being accomplished by overhead buckets, funnels, or spouts that disperse a metered amount of the product into each individual container.
After the product is placed in the container, a sheet of material is sealed to the top of the containers. Packaging devices often use heat sealing assemblies to seal the sheet of covering material to the containers.
The containers are transported in metal container carriers along the assembly line in a predetermined direction at a predetermined speed. A roller chain is often used to move the container carriers continuously along the assembly line path. The sheet of material covering the containers is typically a continuous sheet. Therefore, after the containers are filled and sealed, the film sheet must be cut so that the containers may be separated from each other.
It is known to provide a film sheet cutting assembly which is rotated in an orbital path so that the cutting assembly moves above each of the container carriers as the container carriers pass below the cutting head assembly. A typical cutting head assembly includes first and second knife blades which pass between adjacent container carriers on opposite sides of a selected container carrier to cut the sheet of material over the container situated in the selected container carrier. A common drive shaft and gears are used to synchronize the movement of the cutting assembly with movement of the carriers. By timing the movement of the cutting assembly with the carriers, the common drive shaft and gears cause first and second knife blades to penetrate gaps between the carriers and cut the sheet of material. Conventional systems rely exclusively on this timing to align the cutting assembly with the container carriers.
Problems have risen in recent years as the characteristics of the covering material have changed. In years past, a thin film sheet was used to seal the containers. The containers were then placed into a visually appealing cardboard box. However, more sophisticated coatings or covering materials have been developed in recent years. These include thicker cardboard sheets or metal films. No outer carton or box is required for these new containers. Therefore, less waste products are produced when the new covering materials are used to seal the containers.
The development of these sophisticated new covering materials has caused problems to arise when the sheet of material is cut by the cutting assembly after the containers have been sealed. The blades of the cutter must dive deeper between the container carriers in order to cut the thicker new materials. This increases the likelihood that the knife blades will be broken during the cutting operation. Particularly, as the knife blades enter and exit the gap between the adjacent carriers the blades can strike the edges of the container carriers and break.
One object of the present invention is to provide a mechanism which maintains alignment of the cutting head assembly with the container carriers during a cutting operation to reduce the likelihood that the knife blades will be broken during the cutting operation.
According to the present invention, a cutting assembly is provided for cutting a continuous sheet of material covering containers which are continuously conveyed in spaced apart container carriers in a predetermined direction at a predetermined speed. The cutting assembly includes a support assembly and means coupled to the support assembly for rotating the support assembly in an orbital path so that the support assembly passes above the container carriers at substantially the predetermined speed and direction during a first portion of the orbital path. The cutting assembly also includes means coupled to the support assembly for cutting the continuous sheet of material as the support assembly moves above the container carriers during the first portion of the orbital path. The cutting assembly further includes means for aligning the cutting means with respect to the container carriers as the cutting means cuts the sheet of material.
In the illustrated embodiment, the support assembly includes first and second spaced apart mounting plates and a cutting head assembly is pivotally coupled to the mounting plates for supporting the cutting means. The aligning means includes a pin member coupled to the cutting head assembly and means for receiving the pin member therein to align the cutting means relative to the container carriers. The receiving means includes a roller chain used to move the container carriers at the predetermined speed and direction. The roller chain has a plurality of rollers for moving the container carriers. The pin members are configured to enter a space between adjacent rollers of the roller chain or indentation in carrier plate to align the cutting means relative to the container carriers.
Also in the illustrated embodiment, the support assembly includes at least two pivot arms coupled between the first and second mounting plates and the cutting head assembly to permit the cutting head assembly and the cutting means to move relative to the support assembly. This advantageously permits the aligning means to compensate and adjust a slight misalignment of the cutting means with respect to the container carriers.
The illustrated embodiment of the present invention also includes a tie bar coupled between the first and second mounting plates and means coupled between the pivot arms and the tie bar for limiting the rate of movement of the cutting head assembly and the cutting means relative to the support assembly. The movement limiting means advantageously prevents a rapid movement of the cutting means relative to the container carriers to reduce the likelihood that the cutting means will be damaged during a cutting operation.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of a preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.